Machining AR-15 upper forgings

It takes so long to generate a meaningful post (complete project) that we’re going to try posting progress pics.  Consider these a teaser.  When the project is done, I’ll publish a complete tutorial, with dimensions.  Until then, here’s what we’re working on…

We got some AR-15 upper receiver forgings (both ‘A2 and ‘A3 style).  After quite a bit of planning (these are more difficult than the lower), we’ve started making chips.

Aligning the first setup

Aligning the first setup

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Wednesday Book Review: Hatcher’s Notebook

Hatcher's Notebook

Hatcher’s Notebook


Julian Hatcher (1888-1963) is about as closely aligned with firearms as a person could be.  Raised in the same time period that saw the innovations of pump-action, lever action, and self-loading rifles and pistols and machine guns, his life spanned a period that encompassed the greatest advances in firearms.  He held positions in Army Ordnance, the NRA, and numerous competitive shooting organizations as well as writing and editing for several firearms periodicals.

Perhaps most notably, he was the Officer In Charge of the Springfield Armory Experimental department and participated in numerous studies and experiments spanning a broad range of firearms design related subjects.

During these years, he kept notes, and these were eventually compiled into a book Hatcher’s Notebook – a veritable cornucopia of information about firearms, designs of the times, and experiments that most of us would find impractical to conduct given that we don’t have the financial backing of the government.

In 1957, he updated Hatcher’s Notebook to include some new material.  That work, the 1957 edition of Hatcher’s Notebook, is a goldmine of firearms history, design detail, and observation that is unlikely to ever be reproduced in the public or private sector.

It is nearly impossible to review Hatcher’s Notebook without providing a laundry list of material covered as the topics explored range broadly across virtually all aspects of firearms.  Among the items mentioned on the front cover are: automatic mechanisms, machine guns and semi-automatics, barrel obstructions, rifle strengths and weaknesses, exterior ballistics, recoil problems, headspace, triggers, caliber equivalents, range, and gunpowder.

I know of no other firearms manual which so directly addresses the broad study of firearms design.  It is, however, an old manual and suffers slightly in some regards.  Hatcher’s discussion of ‘spin drift’, for example, contains conclusions that are now considered erroneous.  Fortunately such errors are few and far between.

This is a book that undoubtedly belongs on the shelf of anyone engaged in firearms design, but it is not perfect.

4.5 stars

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Making a Hammer-Fired Trigger Module for Prototyping

One of the things I’d like to attempt as this site builds up to actual design of firearms, is to create some modular pieces that can be used when other parts of the design are the point of interest. As an example, relevant to today’s article, if you wish to experiment with a new breech-locking mechanism, the design and assembly of a trigger is a nuisance – you need a trigger, but the time and energy spent creating it are a distraction from the thing you are really trying to test.

To that end, a trigger module, or cassette, is a desirable unit to have kicking around in one’s toolbox. In reality, several trigger cassettes might be useful: one to activate a hammer and one to release a striker. Today, we’ll look at a simple hammer-type trigger cassette utilizing AR-15 trigger components.


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Friday Links

Since we’re on the topic of triggers, here are a few links related to trigger design in addition to some general interest links.

The first is a PDF of the Remington-Walker trigger.

and an explanation of the Savage Accu-Trigger.

An interesting calculator to help figure gas pressures that may help in designing gas operated firearms.

Of course you’ve probably heard of making an AR-15 on a 3D printer by now.

Finally, while the explanations are basic, there are some excellent illustrations of firearms actions in the HowStuffWorks Machine Gun article.

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Wednesday Book Review: The Ultimate Thompson Book

The Ultimate Thompson Book
by Tracie L. Hill <copyright> 2009
Collector Grade Publications
ISBN: 0-88935-496-0

Ultimate Thompson Book

The Ultimate Thompson Book

The Ultimate Thompson Book is a heavy, handsome, and expensive tome that chronicles the entire development of arms under the direction of General John Thompson as well as the legacy of the company he helped create, Auto Ordnance. The book is aimed at historians and collectors, but is happily technical enough to warrant reading by those interested in firearms design as well.

In 1916 General John Thompson founded Auto-Ordance Corporation with the intention of creating an “Auto Rifle” – a self-loading rifle of such size and weight that it could serve in lieu of the standard rifle of the time, the M1903 Springfield.  His ace in the hole revolved around his acquisition of the rights to the “Blish principle” – what engineers today would call static friction, or ‘stiction’.  Thompson hoped that the Blish principle would allow the creation of a small, lightweight breech-locking mechanism that would make such a rifle possible.  To explore such possibilities he hired Theodore Eickhoff, Oscar Payne, and others to design such a firearm.  Several prototypes of the “Thompson Auto Rifle” were developed, but none of them faired satsifactorily in ordnance trials.  However, serendipitously, a byproduct of the rifle development was the discovery that the principle appeared to work exceedingly well in .45 ACP and the Thompson Submachine Gun, or “Tommy” gun was born.  Too late to see use in WWI, the Tommy gun was refined repeatedly as Thompson tried to sell the design to foreign militaries, law enforcement, and others.  Unhappily, the Thompson found its first enthusiasts within organized crime, an association that persists to this day.  At the beginning of WWII, Auto-Ordnance had sold a relatively small number of Tommy guns (fewer than the original manufacturing run of 15,000), but the war brought acceptance and demand.  During the course of the war, the original design was simplified for mass production and economy by engineers at Savage Arms, resulting in the M1 series Thompsons.  Post WWII saw demand for the Thompson diminish significantly, and as time passed, the design has faded in and out of popularity.  Today, nearly 100 years later, Thompsons are still in use.  Originals are much prized by collectors and shooting enthusiasts and several semi-automatic versions are still being manufactured.

The Ultimate Thompson book covers this history in exquisite detail.  The bulk of the book is organized chronologically, so intermingles biographies of key players, financing, politics, and of course, design.  The book is striking for its copious use of illustrations.  Having read many books and articles from this time frame, I thought the quality of the photographs and drawings exceptional.  The story is divided into many bite-size pieces, making the book easy to read in snippets as well as excellent as a reference.  The writing is excellent, and engaging, making the book a very enjoyable read.  Though it lacks an index, the Table of Contents is quite detailed and readily usable by anyone familiar with the story.

Of particular interest to the firearms designer, the book details the manner in which the original design goal (the Auto Rifle, remember?) was approached.  Early test setups are shown and described, as well as experimental mechanisms used during development.  Changes and improvements, as well as their motivations are also discussed.

While primarily of interest to collectors, the latter portion of the book details such things as appearances of the Tommy gun in movies, as toys, and in pop culture, as well as providing a list of known Thompson’s.

“The Ultimate Thompson Book” is one that truly lives up to its title, leaving no stone unturned, and detailing the Thompson firearms as never before.  It is an extraordinarily complete volume of the highest quality.  Valuation is always a subjective proposition, and someone with little interest in the Tommy gun may not enjoy this book as much as I did, but as a Tommy enthusiast, the hefty $150 I paid for my copy was money well spent.

5 Stars.

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